New Research Challenges Marijuana Gateway Theory


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​The widespread belief that marijuana users will eventually and inevitably move on to harder drugs has yet more evidence against it with the release of a new study from the University of New Hampshire.

Whether teenagers who smoked pot will use other illegal drugs as young adults has a lot more to do with factors such as employment status and stress, according to the new research, reports Science News. In fact, the strongest predictor of whether someone will use hard drugs is their race/ethnicity, not whether they ever used marijuana.
“In light of these findings, we urge U.S. drug control policymakers to consider stress and life-course approaches in their pursuit of solutions to the ‘drug problem,’ ” wrote UNH associate professors of sociology Karen Van Gundy and Cesar Rebellon.

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​Young adults who didn’t graduate from high school or attend college were more likely to have used marijuana as teenagers and other illicit substances in young adulthood. Additionally, those who used marijuana as teenagers and were unemployed following high school were more likely to use other illicit drugs.
But the association between teenage marijuana use and other illicit drug use by young adults fades once stresses such as unemployment diminish.
“Employment in young adulthood can protect people by ‘closing’ the marijuana gateway, so over-criminalizing youth marijuana use might create more serious problems if it interferes with later employment opportunities,” Van Gundy said.
Once adults reach age 21, the gateway effect goes away entirely.
“While marijuana use may serve as a gateway to other illicit drug use in adolescence, our results indicate that the effect may be short-lived, subsiding by age 21,” the researchers said. “Interestingly, age emerges as a protective status above and beyond the other life statuses and conditions considered here. We find that respondents ‘age out’ of marijuana’s gateway effect regardless of of early teen stress exposure or education, work, or family statuses.”
The strongest predictor of other illicit drug use appears to be race/ethnicity, not prior use of marijuana, according to the research.
Non-Hispanic whites show the greatest odds of using hard drugs, followed by Hispanics. Least likely to use hard drugs are African-Americans, the research indicated.
The research appears in the September 2010 issue of the Journal of Health and Social Behavior in the article, “A Life-Course Perspective on the ‘Gateway Hypothesis.’ “
The scientists used survey data from 1,286 young adults attending Miami-Dade public schools in the 1990s. Within the final sample, 26 percent of the respondents are African-American, 44 percent are Hispanic, and 30 percent are non-Hispanic white.
Past research had already largely invalidated the gateway theory. Most recently, in January a study was released indicating that marijuana use actually discourages hard drug use.
A 2002 RAND study dismissed the gateway theory and raised doubts about the legitimacy of federal drug policies based upon its premise.